An oxygenator unit adapted for the use in an extracorporeal blood treatment device. The oxygenator unit includes an oxygenator having a gas inlet and a supply line for conducting a gas provided at the gas inlet, the supply line being connectable to a source of a pressurized gas containing oxygen, wherein the oxygenator unit further includes a pressure relief valve provided in the supply line upstream of the oxygenator, the pressure relief valve being adapted to release pressure exceeding a predetermined pressure value from the supply line, thereby preventing a critical overpressure in the oxygenator.